POST UTME NILE UNIVERSITY 2019 Chemistry | Objective

Practice these randomly selected questions to test your readiness.

Question 1
A 1.00 L flask contains 0.100 M H2(g) and 0.100 M O2(g). If the reaction is allowed to proceed until equilibrium is reached, what is the concentration of H2O(g)?
A. 0.0500 M
B. 0.100 M
C. 0.150 M
D. 0.200 M
Question 2
The half-life of a radioactive subs\tance is 5.00 years. If 100 g of the subs\tance initially exists, how much will remain after 10.0 years?
A. 12.5 g
B. 25.0 g
C. 50.0 g
D. 100 g
Question 3
A 0.5 M solution of HCl is mixed with a 0.5 M solution of NaOH. What is the pH of the resulting solution?
A. 1
B. 2
C. 3
D. 4
Question 4
The reaction between sodium hydroxide (NaOH) and hydrochloric acid (HCl) is a neutralization reaction. Write the balanced chemical equation for this reaction.
A. \( \text{NaOH} + \text{HCl} \rightarrow \text{NaCl} + \text{H}_2\text{O} \)
B. \( \text{NaOH} + \text{HCl} \rightarrow \text{NaCl} + \text{H}_2\text{O}_2 \)
C. \( \text{NaOH} + \text{HCl} \rightarrow \text{NaCl} + \text{H}_2\text{O}_3 \)
D. \( \text{NaOH} + \text{HCl} \rightarrow \text{NaCl} + \text{H}_2\text{O} \)
Question 5
A 2.5 L container is filled with a gas at 25°C and 1 atm. If the gas is heated to 50°C at cons\tant volume, what is the new pressure?
A. 2 atm
B. 3 atm
C. 4 atm
D. 5 atm
Question 6
A 2.50 M solution of HCl is mixed with a 1.00 M solution of NaOH. If the reaction is complete, what is the concentration of the resulting solution?
A. 1.25 M
B. 2.50 M
C. 3.75 M
D. 4.00 M
Question 7
The s\tandard enthalpy of formation of H2O(l) is -285.8 kJ/mol. Calculate the s\tandard enthalpy of vaporization of 1.00 mol of H2O(l).
A. -40.7 kJ/mol
B. -41.7 kJ/mol
C. -42.7 kJ/mol
D. -43.7 kJ/mol
Question 8
A polymer is a large molecule composed of many repeated subunits called monomers. Which of the following is an example of a polymer?
A. DNA
B. Protein
C. Cellulose
D. Water
Question 9
A 2.50 L flask contains 0.500 M H2SO4. What is the concentration of H+ ions in the solution?
A. 0.500 M
B. 1.00 M
C. 1.50 M
D. 2.00 M
Question 10
The boiling point of a subs\tance is the temperature at which the vapor pressure of the subs\tance equals the surrounding pressure. Which of the following subs\tances has the highest boiling point?
A. Water
B. Ethanol
C. Methanol
D. Acetone
Question 11
The pH of a solution can be calculated u\sing the formula pH = -\log[H+]. If the concentration of hydrogen ions in a solution is 1.0 x 10^-3 M, what is the pH of the solution?
A. 3
B. 4
C. 5
D. 6
Question 12
The s\tandard enthalpy of formation of CO2(g) is -393.5 kJ/mol. Calculate the s\tandard enthalpy of formation of CO(g) if the s\tandard enthalpy of formation of O2(g) is 0 kJ/mol.
A. -110.5 kJ/mol
B. -393.5 kJ/mol
C. 110.5 kJ/mol
D. 393.5 kJ/mol
Question 13
A 0.500 M solution of NaOH is prepared by dissolving 25.0 g of NaOH in 100.0 mL of water. What is the pH of the solution?
A. 12.0
B. 13.0
C. 14.0
D. 15.0
Question 14
A sample of CO2 gas occupies a volume of 2.5 L at a pressure of 1.5 atm. If the temperature is increased to 300 K, what is the new volume of the gas?
A. 3.75 L
B. 4.5 L
C. 5.25 L
D. 6.0 L
Question 15
Determine the s\tandard enthalpy of formation of NH3(g) from the following data: ΔHf(NH3(g)) = -46.1 kJ/mol, ΔHf(H2(g)) = 0 kJ/mol, ΔHf(N2(g)) = 0 kJ/mol.
A. -46.1 kJ/mol
B. -92.2 kJ/mol
C. -46.2 kJ/mol
D. -92.1 kJ/mol

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